Overheating wowes that make no sense - help!!!

Did you SEE the water pump? Inspect, consider a different pump

Are you sure your temp gauge is correct?

Are you sure the cap is holding pressure?

Air trapped in the block is NOT a big deal on these old engines. People are always suggesting drilling bleed holes in the stat. That's OK, but all you really need to do is yank one heater hose loose or a plug--you want the highest place you can get that is still UNDER the stat, fill until it comes out that point, then go from there

Timing--you sure your timing marks are OK? Bear in mind that a stocker that's cruisin with vacuum adavance runs out into the 50-50's degrees. I'd try running more advance. Mechanical only, about 40 is all you can push, I'd think.

And---how's your fuel? In this day and age........................

Last, get a chemical check (can't remember the name) at a rad shop for a seeping head gasket. It doesn't take but a small seep you might not be "aware" of to inject hot gas into the coolant, and cause puking out the cap.